Is there theoretically any way to detect heat beyond a barrier, without access beyond this barrier?

Like a thermographic camera?

 

That is detect the infrared radiation emitted from hot bodies.

 

What do you mean by a barrier?

well if the barrier is hotter than the surroundings then you can be sure there is a heat source beyond it. if there is an area of the barrier that is hotter than the rest then you can localise it somewhat. but thats the best you can do.

Hm, I was thinking more of some kind of radiation which would penetrate through the barrier (not infrared), the emission of which would be correlated to heat. Suppose the source of heat is a complex chemical system such as a human body.

 

This is all purely hypothetical. It doesn't need to be more than theoretically possible at present.

nope, the only radiation you are going to get is a blackbody emmission spectra of photons.

 

to determine whether this penetrates a barrier or not depends on the barrier.

I don't think people emit blackbody radiation. I'm not a blackbody absorber- I absorb a lot more energy in the parts of the spectrum where water absorbs well. I therefore emit more energy at those wavelengths.

http://en.wikipedia.org/wiki/Kirchhoff's_law_of_thermal_radiation

 

If the wall is transparent to a fair part of the em spectrum you might be able to "see" me behind it at some wavelength or other.

obviously i didn't mean a perfect blackbody spectra but its going to follow it closely enough. i'm trying to keep it basic and uncomplicated here, it is a valid generalisation.